吡那地尔超极化停搏对大鼠离体心脏缺血再灌注时p38MAPK表达的影响

Effect of pinacidil hyperpolarized arrest on p38 mitogen-activited protein kinase expression during myocardial ischemia-reperfusion in isolated rat hearts

目的评价吡那地尔超极化停搏对大鼠离体心脏缺血再灌注时p38丝裂原活化蛋白激酶（p38MAPK）表达的影响。方法成年雄性sD大鼠48只，体重250—300g，采用随机数字表法，将大鼠随机分为6组（Ft=8）：自然停搏组（A组）、St．Thomas组（B组）、吡那地尔超极化停搏组（C组）、5-羟葵酸（5-HD）组（D组）、HMR。1098组（E组）和5-HD＋HMR-1098组（F组）。采用Langendorff离体心脏灌注模型，K—H液平衡灌注15rain后，A组阻断主动脉，不予停搏液灌注，使其自然停搏；B组灌注st．Thomas停搏液；C组灌注吡那地尔超极化停搏液；D组、E组和F组K-H液平衡灌注10min后，分别灌注含5-HD、HMR．1098、5-HD＋HMR-1098的K—H液5min，再灌注吡那地尔超级化停搏液。心脏停跳缺血60min后，K—H液再灌注30min。于平衡灌注15min和再灌注20min时记录冠脉流量（CF）、心率（HR）、左室发展压（IJVDP）、左室收缩压（LVSP）和左室压力瞬时最大变化率（dp，dtmax）；于再灌注30rain时取心肌组织，采用Western blot法测定心肌磷酸化p38MAPK和非磷酸化p38MAPK的表达。结果与C组相比，A组、B组、D组、E组和F组再灌注20min时CF、HR、LVSP、LVDP及dp／dtmax降低，再灌注30min时磷酸化p38MAPK表达下调，非磷酸化p38MAPK表达上调（P〈0．05）；与E组相比，D组和F组再灌注20min时CF、HR、LVSP、LVDP及dp／dtmax降低，再灌注30rain时磷酸化p38MAPK表达下调，非磷酸化p38MAPK表达上调（P〈0．05）。结论吡那地尔超极化停搏可改善大鼠离体缺血再灌注心脏功能，其机制与上调磷酸化p38MAPK表达，下调非磷酸化p38MAPK表达有关，而这种调控作用与线粒体ATP敏感性钾通道关系更密切。

Objective To investigate the effect of pinacidil hyperpolarizaed arrest on p35 mitogen-activited protein kinase （p38MAPK） during myocardial isehemia-reperfusion （I/R） in isolated rat hearts. Methods Forty- eight rome SD rats weighting 250-300 g were randomly divided into 6 groups （ n = 8 each） ： natural arrest group （group A） ; St. Thomas group （group B） ; pinacidil hyperpolarization arrest group （group C） ;5-hydroxydecanoate （5-HD） group （ group D） ; HMR-1098 group （ group E） and 5-HD ＋ HMR-1098 group（ group F） . Langendorff reperfusion model was established and K-H solution was retrogradely perfused for 15 rain. In group A the hearts were arrested naturally after perfusion was stopped; in group B St. Thomas solution was perfused; in group C pinacidil hyperpolarization solution was perfused; in the other three groups, K-H solution was perfused to isolated rat hearts for 10 min followed by 5 rain 5-HD （group D） or HMR-1098（group E） or 5-HD and HMR-1098（$roup F） perfusion, then hyperpolarization arrest solution was given in each group. Each hearts suffered 60 min ischemia after arrest followed by 30 rain K-H solution reperfusion. Coronary flow（CF）, HR, left ventricular developed pres- sure（LVDP）, left ventricular systolic pressure（LVSP） and the maximum rate of pressure rise （dp/dtmax） were measured at the end of 15 min K-H solution perfusion and at 20 rain of reperfusion. Myocardial phosphatic and nonphosphatic p38MAPK expression was determined by Western blot at 30 rain of reperfuslon, Results Cornered with group C, CF, HR, LVDP, LVSP and dp/dtm,, were significantly decreased at 20 rain of reperfusion and phosphatic p38MAPK expression was down-regulated, non-phosphatic p38MAPK expression was up-regulated at 30 rain of reperfusiou in groups A, B, D, E and F （ P 〈 0.05）. Compared with group E, CF, HR, LVDP, LVSP and dp/ dt,na, were significantly decreased at 20 rain of reperfusion and phosphatic p38MAPK expression was down-regulated, non-phosphatic p38MAPK expression was up-regulated at 30 min of reperfusion in groups D and F （ P 〈 0.05）. Conclusion Hyperpolarized arrest induced by pinacidil can improve cardiac function following myocardial I/R injury by up-regulating phosphatic p38MAPK expression, down-regulating non-phosphatic p38 MAPK expres- sion and mitochondrial potassium channel is more important than membranous one during the regulation of phosphatic p38MAPK expression.